Automated data storage libraries are known for providing cost effective access to large quantities of stored data. Generally, data storage libraries include a large number of storage slots on which are stored portable data storage media. The typical portable data storage media is a tape cartridge or an optical cartridge. An accessor robot typically accesses the data storage media from the storage slots and delivers the accessed media to a data storage drive for reading and/or writing data on the accessed media. Suitable electronics both operate the accessor robot and operate the data storage drives to transmit and/or receive data from an attached on-line host computer system.
In a conventional automated data storage library, the storage slots are arranged in a planar orthogonal arrangement forming a "wall" of data storage media. The plane may be a flat plane, or may be cylindrical. To double the storage capacity, two "walls" of data storage media may be provided on either side of the accessor robot.
A number of different companies manufacture automated data storage libraries today, each model displaying various different features. Some automated data storage libraries offer the capability of sharing the entire library with a plurality of hosts. The IBM 3575 Tape Library Dataserver with Multi-Path Feature has the internal capability to allocate drives and storage slots and to handle contentions among the hosts for the same library components. The ATL Products PL50 Library Hub is directed to sharing a library among multiple hosts externally of the library. Hereinafter, the term "logical library controller" is used to refer to the controller with sharing capability, whether it is internal or external to the library.
Conventionally, the components of the automated data storage library, such as data storage drives and storage slots, are sequentially assigned to each of the hosts either automatically (and typically equally) or manually where the operator assigns numbers of the components to each logical library at the host terminal. The assignments are then utilized by the logical library controller for accessing media from the assigned storage slots and directing the accessor robot to deliver the media to the assigned data storage drives in the logical library for each of the separate hosts.
A logical library controller typically comprises a microprocessor, including a database, which may comprise a memory, and input/output adapters, such as SCSI ports. The database typically stores the programs (microcode) which cause the controller to operate the library, and include information indicating the characteristics of the particular library and the logical library assignments. The programs for the controller may be installed or updated by a typical input device, such as a CD-ROM optical drive, but the specific information characterizing the specific library and logical library assignments are typically unavailable externally and only appear in the manually entered database.
The controller memory may fail and require replacement. The microcode may be restored on the replacement memory by installing the microcode at the CD-ROM, but the specific information characterizing the specific library and the logical library assignments would be lost, and would have to be manually entered or manually selected. A difficulty is that there may be no record known by or available to the operator or the memory installer to identify the logical library assignments.